Zone protection apparatus



Dec. 31, 1968 M. P. LEBOURG 3,419,080

ZONE PROTECTION APPARATUS Original Filed 001:. 23, 1965 Sheet of 2 XMaui/re f1 19.60 0/ 9 I NVENTOR.

Dec. 31, 1968 M. P. LEBOURG 0 ZONE PROTECT ION APPARATUS Original FiledOct. 23, 1965 Sheet 2 of 2 flaw? D) "Pq. 1

q Mao/v68 P. ZeAd 19 INVENTOR.

$1 BY dam/m4 ATTGRIVEV United States atent O T 3,419,080 ZONE PROTECTIONAPPARATUS Maurice P. Lebourg, Houston, Tex., assignor to SchlumhergerTechnology Corporation, Houston, Tex., a corporation of Texas Originalapplication Oct. 23, 1965, Ser. N 503,471, new Patent No. 3,389,752,dated June 25, 1968. Divided and this application Sept. 8, 1967, Ser.No. 680,594

4 Claims. (Cl. 166-407) ABSTRACT OF THE DISCLOSURE One embodiment of anapparatus which is illustrative of the present invention includes a bodymember carrying an inflatable elastomer sleeve and an impermeableexpansible liner which surrounds said sleeve and which is attached onsaid body member by hydraulically movable devices. In response to fluidpressure, said devices can be released from engagement with said linerwhereupon inflation of said sleeve will effect expansion of said linerinto sealing contact with the well bore wall.

This is a division of application Ser. No. 503,471, filed Oct. 23, 1965,now Patent No. 3,389,752.

This invention relates generally to oilwell completion methods and, moreparticularly, to the utilization of liners in a well bore to seal andthereby protect a formation zone from the adverse eflects of cementingoperations.

It is generally known that certain types of commercially interestingoil-bearing formations are damaged and their ability to satisfactorilyproduce seriously impaired by cementing operations conducted duringcompletion of the well. For example, low pressure, highly permeable orfractured zones are easily damaged by cement solids or may becontaminated by filtrate. Reef or carbonate formations of vugular orfractured types are adversely affected by penetration of cement solidsinto the voids. Some formations contain water sensitive components thatswell, expand or disintegrate when in contact with cement slurryfiltrate, resulting in decreased permeability. When the aforementionedformation damage occurs the formation fails to produce as anticipatedbased on such productivity indicators as drillstem test data. Expensiveand time-consuming re-perforating or other stimulation is then requiredbefore satisfactory completion can be attained. In some cases, the zonemay have to be abandoned.

It is therefore an object of this invention to provide a new andimproved apparatus for use in completing a well wherein selectedformation zones are protected from damage due to cementing operations.

A further object of the invention is to provide a new and improvedapparatus for use in preventing formation damage during cementingoperations, the apparatus being simple and effective to afford overallcoat savings in oil recovery operations.

With these and other objects in mind, the present invention includes abody member which can be lowered to a point adjacent an impermeable zonein a well bore. The body member carries an inflatable sleeve and animpermeable liner surrounding the sleeve. Hydraulically operable meansare slidably disposed on the body member and serve to releasably attachthe liner on the body member. Upon the application of fluid pressure,the hydraulically operable means releases the liner, whereupon expansionof the sleeve causes the liner to be formed into intimate contact withthe surrounding well bore wall to seal off the formation Zone fromfluids and filtrate in the well bore.

The novel features of the present invention are set forth withparticularity in the appended claims. The in- 3,419,080 Patented Dec.31, 1968 vent-ion, together with the further objects and advantagesthereof may best be understood by way of illustration and example whentaken in conjunction with the accompanying drawings in which:

FIG. 1 is a sectional view of the well bore showing an expandable sealand setting tool therefor positioned adjacent the formation to beprotected from cement damage;

FIG. 2 is a sectional view of the well bore showing the initial settingphase of the expandable seal;

FIG. 3 is a sectional View of the well bore showing the final settingphase and wherein the setting tool of the invention is fully inflatedand the expandable seal in place against the formation wall;

FIG. 4 -is a sectional view of the well bore showing the setting tooldeflated and being withdrawn from the well and the expandable sealremaining in place;

FIG. 5 is a sectional view of the well bore showing casing cementedtherein with the expandable seal protecting the adjacent formation fromcement damage;

FIG. 6 is an elevational half-sectional view of one embodiment ofapparatus for practicing the method of the present invention, thesection taken on line 6-6 of FIG. 1;

FIG. 7 is a section on line 77 in FIG. 6; and

FIG. 8 is an enlarged fragmentary sectional view of the expandable sealadjacent the zone wall.

With reference to FIG. 1, numeral 10 indicates a well bore extendingdownwardly through a permeable formation zone 11 which is to beprotected from cement damage. The well bore contains the usual column ofdrilling mud for control of formation pressures and numeral 12 indicatesthe filter or mud cake which is deposited on the walls of permeableformation zone 11. Means for sealing the formation zone 11, in the formof an expandable liner 13 made of an impermeable, yet elastic andflexible material, is attached to an inflatable setting tool 14, thecombination inflatable setting tool and expandable liner being suspendedin the well bore on a tubular running-in string 15.

Turning now to FIG. 2, liner 13 is shown being expanded out into sealingengagement with the walls of the formation zone 11 by the introductionof pressure into the inflatable setting tool 14 through the running-instring 15. To effectively seal the formation, the setting tool, to bemore fully described below, is so designed that as pressure is increasedtherein the circumferential mid-portion 16 of liner 13 is the firstportion of the liner to contact the filter cake on the zone wall. Assetting of the liner continues, it is progressively pressed out againstthe filter cake from the mid-portion of the liner toward either end. Asshown generally in FIG. 3 and in more detail in FIG. 8, a movableportion 17 of the filter cake is displaced or squeezed out from behindthe liner so that the liner is forced into firm contact with the portion18 of the filter cake remaining between the liner 13 and formation zonewall 19. In this manner the entire peripheral area of the liner isplaced adjacent the zone wall 19 to effect a seal.

Due to the differential pressure between the mud column and theformation fluid, the impermeable liner 13 will stick adjacent the wallof formation zone 11 due to the hydraulic phenomena generally denoted asdifferential sticking and discussed in Mechanics of DifferentialPressure Sticking of Drill Collars, H. D. Outmans, 1958 Journal ofPetroleum Technology, vol. 213, p. 265. Briefly described, the mechanicsof the sticking are such that when the liner is forced into contact withthe filter cake, the flow of filtrate from the drilling mud in the wellbore 10 into the isolated area behind the liner 13 is shut off. Filtratein the cake will continue to flow into the formation, but since nofiltrate can enter the cake, its water content decreases. Decrease inWater content in the isolated part of the cake is accompanied by areduction in porosity and hence in volume. In other words, the cakebetween the liner 13 and the formation wall 19 shrinks as the water issqueezed out of the cake into the formation. As the water contentdecreases the hydraulic stresses throughout the cake decreases untilthey become substantially equal to the formation fluid pressure. Whenthis action has occurred, the pressure differential between the mudcolumn pressure and the formation fluid pressure will act radiallyoutwardly across the entire peripheral area of the impermeable liner 13to hold the liner in firm sealing engagement over the zone Wall 19Without the need for an anchoring device thereby protecting theformation zone from invasion to cement slurry or filtrate.

Furthermore, as the filter cake shrinks, the diameter of the liner 13increases and the mud column pressure acts over an increasingly greaterperipheral area of the liner. Thus, the liner 13 becomes increasinglymore stuck adjacent the formation zone wall and greater forces will berequired to dislodge the liner therefrom. As shown in FIG. 4, settingtool 14 is deflated by bleeding o'lf pressure therein through running-instring 15. After deflation, the setting tool is withdrawn, leaving liner13 in place.

With the formation thus sealed and protected, casing 20 can now be runthrough the sealed zone and cement slurry displaced down through thecasing and up through the annular space between the casing and thesealed zone. As shown in FIG. 5, flow of connate fluids from formation11 into the casing 20 is established by perforating through casing 20,cement 21, liner 13 and into the sealed zone by a perforator 22 in awell-known manner.

Apparatus suitable to perform the method is shown in FIG. 6. Inflatablesetting tool 14 has a central body including a mandrel 23 which isthreadedly coupled at its upper end to running-in string 15 and closedat its lower end by a plug 24. A plurality of ports 25 extend throughthe mandrel wall and provide communication between the bore 26 of themandrel and the annular space 8 enclosed by a sleeve or bladder 27 madeof rubber or other elastomeric material. The sleeve 27 is attached tomandrel 23 at an upper end 28 by cap member 29 and at a lower end 30 bycap member 31, the joints 32 between the ends of the sleeve and thecaps'being hermetically sealed in a suitable manner. The wall thicknessof sleeve 27 increases gradually from the thinnest portion 33 at itsmid-portion to thicker portions 34, 35 near each end, thereby permittingcontrol of the progress of inflation of the sleeve.

A tube 48 is provided for by-passing fluids through the inflatablesetting tool 14 as it is being shifted longitudinally through thefluid-filled well bore. The tube 48 communicates with a port 49 in theplug 24 and extends upwardly through mandrel 23 to a second port abovethe upper cap member 29, thereby placing the spaces above and below thesetting tool 14 in communication.

Attached to the exterior of setting tool 14 is the expandable seal orliner 13 made of a flexible yet i'mpermeable material such as acylindrical sheath of a soft steel or other metal having approximately aA wall thickness. Alternatively, a cylindrical sheath of a suitableplastic can be used. The inside surface of the liner may be suitablyprepared for optimum bonding to cement by sandblasting or the like. Toreduce the outside diameter of liner 13 so that it may be expeditiouslyrun into the well bore, longitudinal folds or corrugations 36 may bemade therein as shown in FIG. 7.

Upper and lower means 37 for releasably attaching the liner 13 to theexterior of setting tool 14 are provided. Both means being identical inconstruction, only the upper means will be described. An annular sleevepiston 38 is slidably disposed about mandrel 23. Piston 38 is secured toa tubular skirt 39 which extends slida'bly over the exterior of head 40above cap member 29. The length of skirt 39 is such as to provide asealed expansible pressure chamber 41 between the upper end of head 40and piston 38. Ports 42 extend through the wall of mandrel 23 andprovide communication between the interior of the mandrel and pressurechamber 41. Alternatively, vertical ports (not shown) may be providedthrough the cap member and head to place chamber 41 in communicationwith the space S between the sleeve and mandrel. A helical compressionspring 43 is disposed around mandrel 23 between the top of piston 38 andtubing collar 44. Extending outwardly from the lower end of skirt 39 isan annular flange 45 having an outside diameter at least as great as thereduced diameter of liner 13 so that any obstructions met while loweringthe apparatus into the well bore will not act to dislodge the liner fromthe setting tool. Depending downwardly from flange 45 are a plurality ofnotched retaining fingers 46 which engage the ends of liner 13 andsecurely hold it in place on the setting tool. Brace members 47 may beprovided to aid in passing borehole obstructions.

In operation, the structural organization of parts shown in FIG. 6 islowered into well bore 10 and positioned adjacent the formation to beprotected 11. A suitable pressure medium is introduced down throughrunning-in string 15 and passes through ports 25 into the space S, thusacting to expand sleeve 27. It will be appreciated, of course, that theapparatus could be run on a wireline and a down hole pump used toinflate the sleeve.

As mentioned above, due to variation in cross-sectional thickness ofsleeve 27, expansion will begin at mid-portion 33 and progress towardeach end. The mid-portion of expandable seal or liner 13 will thereforebe the first portion to engage the filter cake 12 on the formation walland sleeve 27 will act to apply the liner from its midportion towardboth ends. This mode of applying the liner, as previously explained,will act to displace a movable portion of the filter cake from behindthe liner and expedite the forming of a good seal.

The aforementioned pressure, transmitted via ports 42, moves pistons 38against springs 43 to disengage the notched fingers 46 from the ends ofthe liner 13. This releases the liner from the setting tool 14 forapplying the liner to the formation wall. Continued application ofpressure to setting tool 14 will fully inflate sleeve 27 and firmlypress the entire outer surface of liner 13 into sealing engagementadjacent the formation zone wall 19.

Setting tool 14 is deflated for removal by bleeding off pressure fromwithin sleeve 27 through running-in string 15. The elastomeric sleevemember 27 will return to its normal, unstretched size and the settingtool can be withdrawn from the well.

In use of the present invention, after the well is drilled and beforecasing is run and cemented, the inflatable setting tool and anexpandable liner are lowered into the well bore until the liner isadjacent a selected hydrocar hon-bearing formation susceptible to damageby cementing operations. The setting tool is then actuated to expand theliner out against, and into sealing engagement with, the formation wall.Controlled expansion of the liner acts to displace a movable portion ofthe filter cake on the formation wall so that an effective seal is madeby the liner. When the liner comes into contact with the filter cake,the filtrate flow is shut off and differential sticking is permitted asheretofore described. If desired, the setting tool is maintained in itsfully inflated condition for a period of time to insure stabilization offilter cake fluid pressure and formation fluid pressures behind theliner.

The setting tool is then deflated and withdrawn from the well bore,leaving the liner in place. The pressure differential betweenhydrostatic mud column fluid pressure and formation fluid pressure actsto hold the impermeable liner in place and effectively seal theformation zone. Casing may now be run through the zone and cemented inplace, the liner preventing contact between the cement slurry and theformation and thereby protecting the formation from cement damage. Tocomplete the well, perforations may be made through the casing, cementand liner so that flow of connate fluids from the formation into thecasing is permitted.

It will be readily seen that a new and improved apparatus for use incompleting a Well has been disclosed wherein formation zones can beprotected from damage during cementing operations. The invention issimple and eflective and will afiord overall cost savings in oilrecovery operations by eliminating the need for remedial work to attainsatisfactory production from formation zones which have sustained cementdamage. Since certain changes may be made without departing from thescope of the inventive concept involved, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. Apparatus for use in a well bore comprising: a hollow body, aninflatable elastomer sleeve about said body; means providingcommunication between the interior of said hollow body and the interiorof said elastomer sleeve so that pressure applied to said body will actto inflate said elastomcr sleeve; an impermeable expandable linerreleasably attached to said body and positioned to surround said sleeve;and hydraulically operable means engaging the ends of said liner forattaching said liner on said body, said hydraulically operable meansbeing slida bly disposed on said body and operable in response topressure within said body for releasing said liner from attachment tosaid body.

2. Apparatus as recited in claim 1, wherein the expandable liner haslongitudinal corrugations initially formed therein to reduce the outerdiameter thereof.

3. Apparatus as recited in claim 1, wherein said hydraulically operablemeans includes a piston and skirt forming an expansible chamber; andfingers initially en gaging said liner and movable with said piston.

4. Apparatus as recited in claim 1, and further comprising a means onsaid body for placing the space above and below the sleeve incommunication.

References Cited UNITED STATES PATENTS 2,583,316 1/1952 Bannister 166207X 2,796,134 6/ 1957 Binkley 166207 2,812,025 11/1957 Teague et al.166-207 3,047,065 7/1962 Vincent 16614 3,111,991 11/1963 ON eal 166-2073,134,442 5/1964 Jennings 166207 3,326,293 6/1967 Skipper 16614 X DAVIDH. BROWN, Primary Examiner.

